The artificial structure-evolution-design of multiphase-composite films for dielectric energy storage

Dielectric capacitors with the ultra-high power density and ultra-fast charge-discharge speeds attracted great interest in electronic devices. Multiphase composite engineering is emerged as a favorable strategy to boost the energy performance of dielectric capacitors. However, the details of composite film growth mechanisms, and how microstructure influences the energy storage performance are still ambiguous. Herein, the BaHf_0.17Ti_0.83O₃-25 %HfO₂ (BHT17–25HfO₂) multiphase composition films with various microstructure are obtained to shed light on the modulation mechanism of growth temperature on the microstructure and energy storage performance. The lamellar and fibrous HfO₂ distributed in BHT17–25HfO₂ films not only can form the insulated networks to hinder large injection of electric carriers for strengthening the E_b, but also can attenuate the interaction of polar structure and suppress the polar structure contributions to lessen the hysteresis loss. The reduced hysteresis loss and enhanced E_b of lamellar and fibrous mixed structure BHT17–25HfO₂ films synergistically improve energy storage performance with the W_re of 122.35 J·cm⁻³ and η of ∼ 80 % at room temperature. Besides, an excellent thermal stability in the wide temperature range from −100 °C to 325 °C (W_re: 84.82 J·cm⁻³, η ∼ 80 %) and the outstanding high temperature antifatigue properties also are achieved. Our work offers a new avenue toward microstructure design of dielectric film capacitors for superior energy storage performance and establishes the relationship between microstructure and properties of dielectric composite films for energy storage performance.